Er, read the post! It refers to diane abbot alone as the three wise monkeys. The lack of punctuation makes that very clear. Also, based on the posters previous comments it is clear they only used the specific term due to the race involved.
Stop standing up for racists.
Assuming that your description is accurate, you are correct. It is a dog whistle - something that other racists can snigger at and at the same time deny it is racist.
I have not read who posted the offending item but it sounds like something that droopy rectum has been doing for years.
Meanwhile you can be held up as a typical whining lefty, offended on behalf of other people. Who knew, eh?